In recent years the fabrication of products in the form of, or conversion from, an indefinite length web of material has become a popular method of manufacture whenever the product lends itself to such methods. High production rates and lower costs are often obtained when web based manufacturing can be used. A well-developed art has grown up around the need for moving and handling indefinite length webs when such web based methods are used.
Dead-shaft idler rollers are commonly used to support and/or deflect indefinite length webs during production processes. It is usually desirable to construct such idler rollers to present minimal rotational friction to the web being supported. Energy losses caused by rotational friction in the idler roller must be made up by the transfer of kinetic energy from the web to the idler roller. This is undesirable for several reasons, including the possibility of loss of precision tension control over the web.
Dead-shaft idler rollers are generally preferred over similar live-shaft rollers for various reasons. Dead-shaft rollers have less roll face deflection than a similar live-shaft design because its bearings are located in headers, i.e. closer to the center of the roll. Precision grinding of a dead-shaft roll is typically less complicated than for a live-shaft roll of comparable size and capacity in terms of mounting, aligning, and driving the roll in the grinding machine. Additionally, it is easier to mount and maintain the alignment of dead-shaft rollers on manufacturing equipment than live-shaft rollers.
Another type of roller also often used in web-based manufacturing is a temperature controlled roller. In some processes, it is desirable to add or remove thermal energy from the web at some stage of production processes. Electrical heaters can be used to impart energy (heat). However, rolls that are heated or cooled by fluid are also known to the art and have their advantages over electrically heated rollers. For example, water is a very efficient and safe medium to transfer heat to a web. Fluid or water heated rolls can be controlled more responsively than electrically heated rolls. Further, fluid such as water can both heat and cool relative to room temperature. There are numerous expedients discussed in literature that allow fluid to be circulated through a temperature controlled roller while it is spinning. However, these expedients all pertain to live-shaft rollers. The art would be well served by the discovery of the mechanism by which the advantages of fluid-based temperature-controlled rollers could be combined with the advantages of dead-shaft rollers.